The New Yorker. I don't think I've seen this picture before and I can't stop looking at it. I grabbed this version from the iPad app. In the magazine you can see more width.
It was taken on the morning of November 22nd 1963 as John F. Kennedy left his Fort Worth hotel to go to Dallas. The first thing that struck me was the lack of obvious security. I suppose the men in white macs on the left are Secret Service but they're behind the President not in front of him. The cameramen are wandering free, not behind a red rope. In the magazine version you can see that the public have been corralled at the other side of the road but still it's very relaxed.
In the accompanying feature, written by Robert Caro (who is four volumes in to a five-part biography of Lyndon Johnson) we learn that it was raining that morning, that Johnson took off his hat because he realised it made him look old next to the bare-headed President and that Kennedy's nervous habit of checking his jacket button was connected with the fact that he wore a form of corset which was held in place by an elastic bandage that wrapped round his back and thighs "in a figure eight pattern".
A few hours after the picture was taken Kennedy was dead and Johnson, who had thought his political career was over, was being sworn in as President in a carefully stage-managed photo op featuring the dead man's wife. They include that familiar picture as well but I love the boldness with which this first picture is used. Once you've seen it you can't imagine any other way of doing the story.